1. Field of the Invention
The present invention relates to a printed circuit board including a via pad with concavo-convex patterns of various shapes and a method of manufacturing the same.
2. Description of the Related Art
A printed circuit board (PCB) is a circuit board which plays a role of electrically connecting or mechanically fixing predetermined electronic components and consists of an insulating layer made of a phenol resin or an epoxy resin and a copper foil layer attached to the insulating layer and having a predetermined wiring pattern formed thereon.
At this time, the PCBs are classified into a single-sided PCB in which wiring is formed on one surface of an insulating layer, a double-sided PCB in which wirings are formed on both surfaces of an insulating layer, and a multilayer PCB in which wirings are formed in a plurality of layers, according to the number of stacked layers.
Recently, high density of a build-up substrate is required due to miniaturization, thickness reduction, and high density of electronic products, and a high reliability substrate is required at the same time.
Like this, in order to secure high reliability of the substrate, an insulating material having a low coefficient of thermal expansion (CTE) and a high glass transition temperature has been developed, and in order to improve via connection reliability, a laser via, a desmear solution, and a process have been actively developed.
In general, a via hole is formed on the PCB by laser drilling.
The via hole is formed on a circular or square via pad, which is formed on an insulator, by laser drilling. An upper portion and a lower portion of the via hole are plated by electroless plating or electroplating to be electrically connected to each other.
The shape of the general via pad is larger than a diameter of a bottom of the via hole, and the via pad is formed by copper plating. However, there is a problem of a plating thickness difference due to an area difference between a region where the circuit pattern is formed and a region where the via pad is formed.